1. Field of the Invention
The present invention generally relates to portable lighting devices and, more particularly, is concerned with a flat flashlight device adapted for key ring or chain attachment and having registerable and mateable parts.
2. Description of the Prior Art
Miniature pocket flashlights which can be stored in a pocket or attached to a key chain are known in the prior art. An example of a miniature pocket flashlight is the one disclosed in U.S. Pat. Nos. 4,628,418 and 4,644,451 to Chabria. The Chabria miniature pocket flashlight has a hollow flexible outer case open at opposite ends, a pair of end caps closing the opposite ends of the outer case, a battery receptacle and electrical switch unit disposed in the case which is activated by squeezing the flexible case, and a lamp electrically connected and mounted to the unit and protruding through a hole in one of the end caps on the case (or alternatively the lamp is mounted to a socket in the end cap itself). At least the one end cap is removable in order to replace the lamp and batteries.
The design of the Chabria flashlight embodies at least three major drawbacks. First, the design permits light generated by the lamp to disperse in all possible radial directions from the lamp thus reducing the amount of light projected by the lamp on any one desired location. Second, the design requires that the lamp extend through a hole or from a socket in the end cap of the case. This design requirement leaves the lamp unprotected, exposing it to frequent impacts with extraneous objects while the flashlight is being handled and carried by the user. Such impacts are likely to soon cause breakage of the lamp filament and result in malfunction and premature shortening of the useful life of the lamp. Third, the design requires that one or both of the end caps of the case be frictionally fitted to the ends of the case so as to be readily removable to replace the lamp and batteries. Over time such frictional fits tend to loosen up and allow the parts of the flashlight to come apart. This increases the risk of losing an end cap which would then require the replacement of the flashlight itself.
A thin card-like flashlight device disclosed in U.S. Pat. No. 5,457,613 owned by Lumatec Industries, Inc. of Austin, Tex., and marketed under trademark FLASHCARD, provides a functional and reliable design which overcomes the aforementioned drawbacks of the pocket flashlight design of the Chabria patents. The Lumatec flashlight device provides a package which is relatively thin and flat, has a card-like appearance and handles and feels similar to a credit card with which users are already familiar. The Lumatec flashlight device provides a highly fashionable item as well as providing the lighting function.
In order for the advantages and benefits of the Lumatec flashlight device to be enjoyed by a wider range of users, the inventor(s) herein have perceived a need for a flat flashlight device similar in concept to the prior art Lumatec flashlight device but adapted to accommodate a key ring or chain mode of carrying familiar to users. The inventors herein have also perceived a need for a flat flashlight device easier to assemble than the prior art Lumatec flashlight device.